Control apparatus



June 20, 1950 c. E. BASTON CONTROL APPARATUS Filed Nov. 20, 1947 2 Shets-Sheet 1 INVENTOR WITNESSES:

C riliffiasfofl- QM ATTO EY June 20, 1950 c. E. BASTON W 2,512,295

CONTROL APPARATUS Filed Nov. 20, 1947 2 Sheets-Sheet 2 WITNESSES: INVENTOR Patented June 20, 1950 CONTROL APPARATUS Cyril E. Baston, Glenshaw, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 20, 1947, Serial No. 787,195

' 12 Claims. (01. 200-42) My invention relates, generally, to control apparatus and, more particularly, to fluid-pressure operated switches of the type utilized in railway control systems and commonly known as unit switches.

A special cam-controlled air-operated unit switch is described in my copending application Serial No. 535,837, filed May 16, 1944, now Patent No. 2,434,538, issued January 13, 1948. The purpose of providing the aforesaid switch was to simplify the circuits of a control system and at the same time substitute mechanical interlocking for electrical interlocking, thereby increasing the reliability of railway control systems and decreasing the maintenance expense. The force for closing the switch was supplied by fluid-pressure acting upon a piston in a c linder, and the valve for admitting the fluid to the cylinder was located inside the cylinder and operated by a cam disposed externally of the cylinder.

The aforesaid switch was found to be di'flicult to manufacture and an object of my present invention is to provide a simplified and improved *unit switch which shall be efiicient in operation and which may be economically manufactured.

Another object of my invention is to provide an air-operated cam-controlled switch having the controlling valve and cam located externally of the switch cylinder.

A further object of my invention is to interlock mechanically the switch actuating mechanism and the controlling cam.

Still another object of my invention is to so interlock the switch actuating mechanism and its controlling valve and cam that neither the switch nor the cam can operate improperly.

A still further object of my invention is to control the sequential operation of a plurality of air-operated cam-controlled unit switches.

Other objects of my invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with one embodiment of my invention, the operation of an air-operated switch is controlled by an externally disposed valve which is operated by a rotatable cam driven by a shaft which drives the cams for a plurality of other switches in a control system. Each switch actuating mechanism is so mechanically interlocked with the cam shaft that rotation of the shaft is stopped if the switch fails to respond to the operation of its controlling valve, thereby preventing operation of the other switches in the system.

For a better understanding of the nature and 2 objects of my invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a view, partially in side elevation, and partially in section of a portion of a switch structure embodying the principal features of my invention;

Fig. 2 is a view, in front elevation, of the structure shown in Fig. 1, and

Fig. 3 is an enlarged view, in section, taken along the line III-III of Fig. 1.

Referring to the drawings, and particularly to Fig. 1, the structure shown therein comprises a switch H], which is of the type commonly known as a unit switch, and a cam group I! for controlling the operation of the switch It). The switch l0 comprises a cylinder [2 inside of which is disposed a piston for actuating a movable contact member is into engagement with a fixed contact member I 4 when a suitable pressure fluid, such as compressed air, is admitted into the cylinder l2 through a pipe I 5. The piston is connected to the movable contact member l3 by means of an insulator l6 and a bracket I! for pivotally supporting the contact member l3.

As explained hereinbefore, the switch [0 is of a type well known in the art and it is believed to be unnecessary to describe its structure in more detail. When the pressure fluid is admitted into the cylinder 12, the piston is forced upwardly to compress a spring disposed within the cylinder. The stored energy in the spring forces the piston downwardly when the pressure fluid is permitted to escape to atmosphere.

In order to control the supply of pressure fluid to the cylinder 12, a valve 2| is disposed externally of the cylinder and is connected thereto by means of the flexible pipe [5 and an additional pipe 22. The valve 2| may be connected to a tank (not shown) containing compressed air or other suitable pressure fluid.

The valve 2| is actuated by a lever 23 which is pivotally mounted at 24 on a supporting framework 25. The lever 23 is actuated by a cam 26 which is secured to a shaft 21. The shaft 21 may be driven by an electric motor or an air engine or in some cases it may be operated manually in a manner similar to the usual controller. In case the shaft 2'! is driven by an electric motor, the motor should be connected to the shaft by means of a slip clutch or similar device to prevent injury to the motor in the event that the rotation of the shaft is stopped by a mechan cal into the cylinder 12. with the. cam 25, the switch mechanism must interlock, as will be explained more fully hereinafter.

In order to control the operation of the cam 26 and the shaft 21 to prevent the improper operation of the switch and other switches utilized in the same control system, a bell-crank lever arm 28 is fulcrumed on a shaft 29 which is mounted in the supporting framework25. One end of the lever arm 28 is connected to the operating mechanism for the switch it by a bolt 3 l The other end of the lever arm 29 is provided with a block 32 which cooperates with blocks 33, 34 and 35 secured to the side of a cam 36 to prevent the improper operation of the switch l0 and also to stop rotation of the shaft 21 in case the switch switch. However, if desired, the two cams may be combined into one cam the edge of which is so shaped that it controls the operation of the valve 2| and havin the blocks 33, 34 and 35 so disposed on the side of the cam that the desired operation of the switch is obtained.

As shown in Fig. 2, a plurality of switch units may be controlled by a single cam shaft 27. Additional switch units It and cam groups H similar to the switch l0 and cam group I I may be added. The switches may be caused to operate in It does not operate properly in accordance with the position of the controlling valve 2|.

cam 35 is secured to the shaft 21 and rotates with I The operation of the switch is as follows:

When the contact members of the switch are in 'the open position as shown, the valve 21 is in a position to permit the pressure fluid to be exhausted from the cylinder 12. Assume now that the cam 26 is rotated to cause one of its raised .portions '38 or 39 to engage the lever 23, thereby causing the valve 2'! to admit the pressure fluid Since the cam 35 rotates move upwardly to close the contact members of the switch before the block 32 engages either :the block 33 or the block 35 depending on the direction of the rotation of the cams.

- "These blocks may be so positioned with referjence to the block 34 and the raised portions 38 and 39 on the cam 26 that the lever 2%! is operated by the switch mechanism to cause the block 32 to pass between the block 34 and either the block or the block 35 as the cams are rotated. Thus, if the switch it operates properly in accordance with the position of the controlling valve 2|, rotation of the cam shaft 21 is not stopped by the lever The shaft may continue to rotate to control the operation of the next switch in the group of switches controlled by the cam shaft.

If the switch mechanism does not operate properly. to close the contact members of the :switch, the block 32 will engage either the block .33 or the block thereby stopping the rotation of the cam shaft 21 and preventing the operation of any more switches in the group until the trouble is corrected. Likewise, the block 32 will engage the block 34 to stop rotation of the cam shaft if the switch does not open at the proper time.

'which'the contact members of the switch should close. It is impossible for the contact members of the switch It to be closed with the cam 36 in the position shown in the drawings.

In the structure shown in the drawings, two cams, 2B and 3-5, are provided for each switch. This may be done in order to facilitate the timing .of'the cams tosecure the desired operation of the any desired sequence by so positioning the cam groups on the cam shaft 21 that the proper timing of the switches is secured. As explained hereinbefore, improper operation of any switch or "switches is prevented by the mechanical interlocking between the switch mechanisms and the cam groups, thereby making it unnecessary to provide the large number of electrical interlocks heretofore required in control systems of the type in which the present switches are utilized.

From the foregoing description,.it'is apparent that I have provided a cam-controlled fluid-pressure operated switch structure in which the switch actuating mechanism and its controlling valve and cam are so interlocked that'neither the switch nor the cam can operate improperly. Therefore, the present structure is particularly suitable for utilization in switch groups containing a plurality of switches which must operate in a proper sequence in order to prevent injury to other apparatus in a control system.

Since numerous changes may be made in the above-described construction and difierent embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In control apparatus, in combination, a plurality of sequentially operable switches, each switch having a movable contact member and .a fluid-pressure operated mechanism for actuating said contact member, a valve disposed 'externally of each switch mechanism for controlling the supply of fluid to said mechanism, a rotatable cam for operating each valve, a shaft for driving said cam, stop means driven by said shaft with said cam, and lever means connected to each switch mechanism and cooperating with said stop means to stop the rotation of said shaft.

2. In control apparatus, in combination, a plurality of sequentially operable switches, each switch having a movable contact member and a fluid-pressure operated mechanism for actuating said contact member, a valve disposed externally of each switch mechanism for controlling the supply of fluid to said mechanism, rotatable cam means for operating each valve, a shaft for driving said cam means, stop means driven by said shaft with said cam means, and a lever arm connected to each switch mechanism and cooperat- 'ing with said stop means to stop the rotation of said shaft.

3. In control apparatus, in combination, a plurality of sequentially operable switches, each switch having a movable contact member and a fluid-pressure operated mechanism for actuating said contact member, a valve disposed externally of each switch mechanism for controllin the supply of fluid to said mechanism, rotatable cam means for operating each valve, spaced blocks mounted on said cam means, a shaft for driving said cam means, and a lever arm connected to each switch mechanism and cooperating with said blocks on the cam means to stop the rotation of said shaft.

4. In control apparatus, in combination, a plurality of sequentially operable switches, each switch having a movable contact member and a fluid-pressure operated mechanism for actuating said contact member, a valve disposed externally of each switch mechanism for controlling the supply of fluid to said mechanism, rotatable cam means for operating each valve, spaced blocks secured to said cam means a shaft for driving said cam means, and a lever arm connected to each switch mechanism and cooperating with said blocks on the cam means to stop the rotation of said shaft and prevent the improper operation of its switch.

5. In control apparatus, in combination, a plurality of sequentially operable switches, each switch having a movable contact member and a fluid-pressure operated mechanism for actuating said contact member, a valve disposed externally of each switch mechanism for controlling the supply of fluid to said mechanism, rotatable cam means for operating each valve, a shaft for driving said cam means, a lever arm connected to each switch mechanism, and stop means secured to said cam means and cooperating with said lever arm to stop the rotation of said shaft and prevent improper operation of the valves for said switches.

6. In control apparatus, in combination, a plurality of sequentially operable switches, each switch having a movable contact member and a fluid-pressure operated mechanism for actuating said contact member, a valve disposed externally of each switch mechanism for controlling the supply of fluid to said mechanism, rotatable cam means for operating each valve, a shaft for driving said cam means, a lever arm connected to each switch mechanism, and stop means secured to said cam means and cooperating with said lever arm to stop the rotation of said shaft and prevent the improper operation of its switch and the valves for said switches.

7. In control apparatus, in combination, a plurality of sequentially operable switches, each switch having a movable contact member and a fluid-pressure operated mechanism for actuating said contact member, a valve disposed externally of each switch mechanism for controlling the supply of fluid to said mechanism, rotatable cam means for operating each valve, a shaft for driving said cam means, a lever arm connected to each switch mechanism, and a plurality of spaced stop members secured to each cam means and cooperating with said lever arm to stop the rotation of said shaft and prevent improper operation of the valves for said switches.

8. In control apparatus, in combination, a plurality of sequentially operable switches, each switch having a movable contact member and a fluid-pressure operated mechanism for actuating said contact member, a valve disposed externally of each switch mechanism for controlling the supply of fluid to said mechanism, rotatable cam means for operating each valve, a shaft for driving said cam means, a lever arm connected to each switch mechanism, and a plurality of spaced stop members secured to each cam means and cooperating with said lever arm to stop the rotation of said shaft and prevent the improper operation of its switch and the valves for said switches.

9. In a switch having a movable contact member actuated by a fluid-pressure operated mechanism, in combination, valve means disposed externally of the mechanism for controlling the supply of fluid to said mechanism, rotatable cam means for operating said valve means, a shaft for driving said cam means, a lever arm connected to said mechanism, and stop means secured to said cam means and cooperating with said lever arm to stop the rotation of said shaft and prevent further operation of the valve means 10. In a switch having a movable contact member and a fluid-pressure operated mechanism for actuating said contact member, in combination, valve means disposed externally of the mechanism for controlling the supply of fluid to said mechanism, rotatable cam means for operating said valve means, a shaft for driving said cam means, a lever arm connected to said mechanism, and stop means secured to said cam means and cooperating with said lever to stop the rotation of said shaft and prevent the improper operation of the switch by improper operation of the valve means.

11. In a switch having a movable contact member actuated by a fluid-pressure operated mechanism, in combination, valve means disposed externally of the mechanism for controlling the supply of fluid to said mechanism, rotatable cam means for operating said valve means, a shaft for driving said cam means, a lever arm connected to said mechanism, and a plurality of spaced stop members secured to said cam means and cooperating with said lever arm to stop the rotation of said shaft and prevent further operation of the valve means.

12. In a switch having a movable contact member and a fluid-pressure operated mechanism for actuating said contact member, in combination, valve means disposed externally of the mechanism for controlling the supply of fluid to said mechanism, rotatable cam means for operating said valve means, a shaft for driving said cam means, a lever arm connected to said mechanism, and a plurality of spaced stop members secured to said cam means and cooperating with said lever arm to stop the rotation of said shaft and prevent the improper operation of the switch by improper operation of the valve means.

CYRIL E. BASTON.

REFERENCES CITED UNITE STATES PATENTS Name Date Baston Jan. 13, 1948 Number 

